Population and habitat assessments for conservation: Comparing national strategies for Canadian boreal caribou and Norwegian wild reindeer

Abstract

Habitat loss and fragmentation are major threats to biodiversity. While essential, demographic data alone may be insufficient to rapidly detect habitat-driven population declines and identify efficient management actions. This study explores how conservation strategies can use and integrate demographic and environmental information to detect, monitor and counter population declines. By comparing two extensive conservation strategies for Rangifer tarandus in Canada and Norway, we draw key insights for more comprehensive and actionable strategies. Conservation strategies often use multicriteria approaches combining population and habitat metrics, but seldom succeed in formally integrating these through a causal understanding of habitat-population relationships. The Canadian strategy probabilistically assesses the viability of boreal caribou populations both through direct population modeling, and by statistically linking habitat disturbance to recruitment - thus indirectly capturing habitat-mediated changes in predator-prey dynamics and their consequences on caribou vital rates. The Norwegian strategy develops an expert-based approach to score the quality of wild reindeer populations by combining assessments of habitat quality, connectivity, demography, genetics and health. While the Norwegian assessment is more locally anchored and explores a wider range of drivers, the Canadian one is more targeted and provides a statistical conversion rate between habitat and population metrics. Both assessments serve as a basis for follow-up management actions. This study highlights the need to intensify research to quantify cumulative anthropogenic impacts on the loss of functionally connected habitat, and their consequences on population viability. This would enable early-warning systems for assessing population declines, and help shape more targeted prevention, mitigation and restoration actions.